The bottom line is clear: Our vital interests in Afghanistan are limited and military victory is not the key to achieving them. On the contrary, waging a lengthy counterinsurgency war in Afghanistan may well do more to aid Taliban recruiting than to dismantle the group, help spread conflict further into Pakistan, unify radical groups that might otherwise be quarreling amongst themselves, threaten the long-term health of the U.S. economy, and prevent the U.S. government from turning its full attention to other pressing problems. -- Afghanistan Study Group

Update: SecDef Carter now says specfically that the U.S. will send 217 additional troops to Iraq including special forces and Apache attack helicopters in what is still labeled a "train and advise" mission although in fact U.S. forces are already engaged in combat, and I don't think those helicopters are going to be advising anybody. "Carter said the Mosul effort will bring U.S. troops “closer to the
action” by remaining close to Iraqi forces as they advance toward the
city." The U.S. will also provide $415 million in financial assistance to the peshmerga. The publicly declared number of U.S. troops in Iraq will now be 4,100. (The true number is actually higher as the Pentagon does not count troops on short-term deployment.)